Seabird needs our help — and that might include poisoning mice

The Ashy storm-petrel, a swallow-size seabird, is at danger of extinction because mice are eating its young.

By Graham Chisholm

The Ashy Storm-petrel — a smoky gray seabird about the size of a swallow — is struggling for its existence off the coast of California. And if things continue the way they are, this remarkable species may disappear from the Earth in our lifetime.

It shouldn’t be this way. For a bird that lives almost entirely over our waters, whose problems are almost entirely of our making, we should take some responsibility for its survival, and its ultimate recovery.

Right now, one of the biggest threats to the Ashy Storm-petrel is occurring on the Farallon Islands off San Francisco. As much as this threat puts the survival of the species at risk, it also provides us with a unique opportunity to ensure this bird’s future in California’s natural landscape.

The Ashy Storm-petrel is a species whose survival depends on a delicate balancing act. Despite its small size, it manages to eke out a living almost entirely over the water, avoiding predators and feeding at night. Individuals can live as long as 40 years, and tend to mate for life and return to the same spots to breed year after year.

Because of severe population declines, as well as numerous threats to breeding and feeding habitat, Audubon has put the Ashy Storm-petrel on its watch list. It is also considered a California Species of Special Concern. Although it is one of only two seabirds considered “highly imperiled” in the northeast Pacific by the U.S. Fish & Wildlife Service, an effort to have the bird placed on the Endangered Species List fell short in 2009. As the bird’s total world population has dipped closer to 7,500 individuals, the service has reopened its evaluation and a new decision is pending.

The largest of the bird’s breeding populations is on the Farallones, but counts indicate that the numbers here may be dropping rapidly due to predation by migrant burrowing owls.

Normally the owls wouldn’t be a problem on the Farallones, but now they stay there longer than they would otherwise to feed on large populations of non-native mice. When the mice population fluctuates downward, the owls feed on the Ashy Storm-petrels. It is also suspected that the mice themselves feed on Ashy Storm-petrel chicks.

Over the past 15 years, state and federal wildlife agencies have invested millions in restoring seabird breeding colonies by removing introduced non-native predatory rats and fox from key sites. Seabirds have responded well to these efforts. Now, the U.S. Fish & Wildlife Service is rightfully turning its eye on the Farallones.

As you read this, the service is putting together a plan to rid the Farallones of the invasive mouse population. Under the National Environmental Policy Act, the service must justify its proposal with rigorous science and weigh all the risks and benefits before taking any action. The NEPA process is a good one, one that has produced numerous positive results for wildlife in similar positions as the Ashy Storm-petrel.

If you’ve heard about this issue at all, it has been about the proposed use of a rodenticide to rid the Farallones of the mice. While this rodenticide has been successfully used in other places for this purpose, its potential impacts on other wildlife has prompted many to demand that this option be removed from consideration.

While these issues are all important, it is vital that the ultimate decision about what to do on the Farallones is based on a thorough analysis of the potential impacts on species other than the mice.

We need to do what’s right for the birds and wildlife on the Farallones, not what sounds good in a press release.